Light source modules are widely used in display devices, such as TVs, laptop computers, PDAs, mobile phones and the like. Based on the relative positions between a light source module and a display panel, the display devices can be categorized into a front backlight display device and a rear backlight display device. For the front backlight display device, the light source module is closer to the user than the display panel, and for the rear backlight display device, the display panel is closer to the user than the light source module.